The present invention relates to a semiconductor device and to a semiconductor package, in which an insulating material having a low dielectric constant and a low dielectric dissipation factor is used.
As the speed, degree of integration, and frequency of operation of LSIs have increased, an increase in the signal delay time due to an increase in the wiring capacity has become a problem. While a silicon oxide (SiO2) layer having a dielectric constant of about 4.2 has hitherto been used as an interlayer insulating layer in such devices, a material having a much lower dielectric constant and a much lower dielectric dissipation factor is needed in order to enhance the operating speed of the devices. Examples of a low dielectric constant layer that has been put to practical use at present include a SiOF layer having a dielectric constant of about 3.5. In addition, examples of an insulating layer having an even lower dielectric constant include an organic SOG (spin on glass) layer having a specific inductive capacity of 2.5 to 3.0. However, the characteristics required of the interlayer insulating layer in LSIs include not only a low specific inductive capacity, but also a good heat resistance and high mechanical strength.
In a multi-layer wiring process for an LSI which is miniaturized, the use of CMP (chemical mechanical polishing) as a planarizing technique is indispensable, and, therefore, the mechanical strength of the LSI is an important factor. The organic SOG having a low dielectric constant has the problem that it has a lower mechanical strength than the conventional SiO2 and SiOF layers. In view of this, organic polymer systems having a lower dielectric constant than inorganic insulating layers have been investigated. Among these, polyimide resins have been widely studied since they are highly planar. The polyimide resins, however, have the problem that they have a higher dielectric constant and moisture absorption factor among organic polymers, and, therefore, they are applied to a limited extent to some semiconductor devices, such as bipolar ICs, from the viewpoint of reliability.
Also, in semiconductor packages and in wafer-level packages, in which a package function is formed by a technique involving the extension of the wiring forming process in semiconductor devices, a material having a low dielectric constant and a low dielectric dissipation factor is keenly demanded as an insulating material for a rewiring layer, which is the outermost layer. This is because an increase in the signal delay time due to an increase in the wiring capacity has come to be a problem, as the speed, degree of integration, and frequency have been increased, also in these technical areas. As an insulating material meeting such demands, polyimide resins have been widely used, as in the foregoing. The polyimide resins, however, have the problem that they have a higher dielectric constant and moisture absorption factor among organic polymers.
Furthermore, not only on the wafer level package but also on the basis of general chip-scale packages composed of cut pieces, a material having a low dielectric constant and a low dielectric dissipation factor is keenly demanded as an insulating material to be used in the areas surrounding a wiring layer, from the same viewpoint as indicated above.